Resurrector specialization
Try Warrior. They have a Banner to ressurect players, and the Tactics trait line is specialized in reviving players. You can also have a build with high toughness and vitality and a few skills so you can be more effective.
Another way is trying to go for a thief and stealth yoursellf and your ally while you revive him. With his high mobility, he can reach players faster and quickly disappear.
(edited by K Cross.3458)
All professions have their fair share of support skills. Guardian is the obvious choice, but water ele isn’t a bad idea either. If you’re having trouble because of lag, you could try ranger spirits and just hang out in the back with a longbow. Rangers have two rezes with “spirit of nature” (elite) and “search and rescue” (utility skill). Combined with two other spirits and the traits that make them trigger more often and move around with you provides good support.